1. Technical Field of the Invention
The present invention relates to a method and an apparatus for treating chlorine bypass dust that is recovered from a chlorine bypass system attached to a cement manufacturing facility and gas exhausted from the chlorine bypass facility.
2. Description of the Related Art
Chlorine bypass systems have been used to remove chlorine that may cause troubles such as preheater clogging in cement manufacturing facilities. In recent years, recycling of waste through conversion to cement raw material or fuel has been promoted, which increases the quantity of volatile matters such as chlorine, and the quantity of chlorine bypass dust generated as the quantity of the treated waste increases, which necessitates developments of methods for effectively utilizing the chlorine bypass dust.
From the above-mentioned point of view, in a treatment method through conversion to cement raw material described in Patent Documents 1 and 2, to wastes containing chlorine is added water to allow the chlorine in the wastes to be eluted and filtrated; desalted cake obtained is utilized as a cement raw material; pH of waste water is adjusted to precipitate heavy metals and collect them; and the waste water from which heavy metals are collected is discharged after salt is recovered therefrom or as it is.
In addition, in a method and an apparatus for treating chlorine bypass dust described in Patent Document 3, a slurry obtained by adding water to a chlorine bypass dust is stored, and the stored slurry is fed to a cement finishing process together with at least one selected from the group consisting of a clinker, a gypsum and an admixture, and those are crushed while being mixed in a mill for cement production.
Meanwhile, in a gas exhausted from the above chlorine bypass facility (hereinafter referred to as “chlorine bypass exhaust gas”) is contained high concentration SO2, which necessitates desulfurization treatment. Then, for example, in the Patent Documents 4 and 5, after the chlorine bypass dust is recovered, the chlorine bypass exhaust gas is returned to a cement kiln system for treatment.    Patent document 1: Japan Patent No. 3304300 gazette    Patent document 2: Japan Patent No. 4210456 gazette    Patent document 3: Japan Patent No. 4434361 gazette    Patent document 4: Japanese Patent publication No. 2010-180063 gazette    Patent document 5: Japanese Patent publication No. 2010-195660 gazette